2 In a stand mixer using the whisk attachment, cream the butter and sugar together until light and fluffy, about 3 minutes. Reduce the mixer speed to low and add the flour, 1/2 cup at a time, scraping down the sides of the bowl after each addition. The dough is ready when it holds its shape when squeezed.

3 Separate the dough into four round balls of equal size and roll each into a 1/2" thick 7" disc. Score the top of each disc into eight equal wedges. (Alternatively, press each ball into a metal or wooden shortbread mould dusted with icing sugar and smooth the top with a rolling pin. Remove from the mould before baking.)

4 Bake until the bottoms of the cookies are light gold, 20 to 25 minutes.

5 Sprinkle the tops of the cookies with more superfine sugar while they’re still hot; let the cookies cool on a rack before breaking into wedges to serve.